With recent advances in image display technology, touch screens, used to input data by direct contact, have gained ground as display apparatuses, are becoming increasingly common in various electronic products, such as small handheld device, current generation smart phones and the like. However, if a multi-touch is generated by two or more substantially simultaneous contact points, the touch panel might malfunction or any one of the touches might be misinterpreted by the related software as an individual input, rather than part of a multi-touch gesture. In order to overcome the limits of multi-touch recognition in the touch panel of the related art, a multi-touch recognition device has recently been developed which simultaneously recognizes a plurality of touches.
One of common techniques employed in conventional gesture recognition devices for recognizing input gesture signals require two or more optical units to perform gesture recognition, wherein each of the optical units consists of a light emitting part and a light receiving part.
For example, U.S. Pat. No. 7,411,575 discloses a gesture recognition method comprising the steps of: displaying an image on a touch surface; capturing images looking generally across said touch surface; processing the captured images to detect pointer contacts on said touch surface and examining said pointer contacts to recognize different successive pointer contacts representing a gesture based on the relative positions of said pointer contacts; and when different successive pointer contacts representing a gesture occur, updating the displayed image in accordance with said gesture. For implementing the method, four cameras are required for multiple touch point detection.
Another example is a display device disclosed in US Patent Publication. No. 2008/0143690, entitled “Display device having multi-touch recognizing function and driving method thereof.” It discloses a display device having a multi-touch recognition function, comprising: an integration module having a plurality of cameras integrated at an edge of a display panel; a look-up-table of a plurality of compensation angles in a range of about 0 to about 90 degrees, corresponding to each of the plurality of cameras; and a processor that detects a touch area using at least first and second images captured by the plurality of cameras, respectively, and compensates the detected touch area with one of the plurality of compensation angles. Four cameras are still required for multiple touch point detection.
Yet another example, U.S. application Ser. No. 12/071,263, proposes a system for distinguishing multiple touch points, comprising: a panel, N touch points being indicated on the panel, N being a positive integer larger than one; a first image capturing unit, disposed on a first position at an outer edge of the panel, for capturing a first image related to the N touch points; a second image capturing unit, disposed on a second position, which is opposite to the first position, at the outer edge of the panel, for capturing a second image related to the N touch points; at least one third image capturing unit, disposed at the outer edge of the panel and between the first image capturing unit and the second image capturing unit, for capturing a third image related to the N touch points; and a processing unit for calculating N sets of coordinates corresponding to the N touch points according to the first image and the second image and for determining one set of real coordinates corresponding to the N touch points from the N sets of coordinates according to the at least one third image. In this method, three image capture units are arranged for multiple touch point detection.
All gesture recognition systems in the prior art require at least two optical units or cameras to perform gesture recognition. The purpose of the invention is to introduce a method to recognize gestures on an optical touch panel with only one optical unit and improve the accuracy of the calculated touch points' locations so as to improve the reliability of the touch panel.